<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
    th,td{
        width: 100px;
        height: 30px;
        border: 1px solid black;
    }
    
    table{
        border-collapse: collapse;
        margin-top: 30px;
    }
    </style>
</head>
<body>
    <table>
        <colgroup>
            <col style="background-color: red">
            <col style="background-color: blue">
            <col style="background-color: orange" span="2">
        </colgroup>
        <tr>
            <th>姓名</th>
            <th>学号</th>
            <th>性别</th>
            <th>年龄</th>
        </tr>
        <tr>
            <td>张三</td>
            <td>123456</td>
            <td>男</td>
            <td>28</td>
        </tr>
        <tr>
            <td>李四</td>
            <td>234567</td>
            <td>男</td>
            <td>29</td>
        </tr>
        <tr>
            <td>汤姆</td>
            <td>345678</td>
            <td>女</td>
            <td>20</td>
        </tr>
    </table>

    <table>
        
        <tr>
            <th style="background-color: red;">姓名</th>
            <th>学号</th>
            <th>性别</th>
            <th>年龄</th>
        </tr>
        <tr>
            <td style="background-color: red;">张三</td>
            <td>123456</td>
            <td>男</td>
            <td>28</td>
        </tr>
        <tr>
            <td style="background-color: red;">李四</td>
            <td>234567</td>
            <td>男</td>
            <td>29</td>
        </tr>
        <tr>
            <td style="background-color: red;">汤姆</td>
            <td>345678</td>
            <td>女</td>
            <td>20</td>
        </tr>
    </table>

    <table>
        <tr>
            <th>姓名</th>
            <th>学号</th>
            <th>性别</th>
            <th>年龄</th>
        </tr>
        <tr>
            <td colspan="2">张三</td>
            <td>男</td>
            <td>28</td>
        </tr>
        <tr>
            <td rowspan="2">李四</td>
            <td>234567</td>
            <td>男</td>
            <td>29</td>
        </tr>
        <tr>
            <td>345678</td>
            <td>女</td>
            <td>20</td>
        </tr>
    </table>
</body>
</html>